1. Field of the Invention
The present invention relates to a novel preparation of trehalose derivatives, more particularly, to a preparation of trehalose derivatives including reacting anhydrous trehalose with a reactive agent under anhydrous conditions.
2. Description of the Prior Art
Recently, there has been interest in acid esters and alkyl ethers of trehalose such as fatty acid esters and sulfonic acid esters of trehalose. Nishikawa et al. reported in "The Chemical Society of Japan", No. 10, pp. 1,661-1,666 (1982) that trehalose esters of stearic acid, palmitic acid, and myristic acid strongly inhibited the growth of malignant tumors both in vivo and in vitro, and implied that these derivatives might be effective as antitumor agents. For example, Japanese Patent Laid-Open No. 290,808/92 discloses that trehalose sulfates satisfactorily retain the water valance of the skin and impart appropriate moisture to the skin. Therefore, these sulfates can be incorporated in some cosmetics as satisfactory humectants and skin-whitening agents. Trehalose ethers with alkyls of 8-25 carbon atoms are known as useful surfactants with a relatively high safety and activity.
As is disclosed by C. K. Lee in "Developments in Food Carbohydrate-2", pp. 1-89 (1980), published by Applied Science Publishers, and K. Yoshimoto in "Chemical and Pharmaceutical Bulletin", Vol. 30, No. 4, pp. 1,169-1,174 (1982), trehalose derivatives are generally prepared by reacting reactive reagents with crystalline trehalose hydrate under anhydrous conditions, and the quality and the yield of the final products especially depend on whether the moisture in the reaction systems can be eliminated to the highest possible degree. However, even when prepared in a solid form, crystalline trehalose hydrate generally contains about 10 w/w % moisture and only results in an unsatisfactory quality and poor yield when used intact. Therefore, crystalline trehalose hydrate is dried to an anhydrous state by using a desiccant such as diphosphorus pentaoxide, prior to use, but the removal of the water of crystallization is substantially difficult. Thus, satisfactorily high quality of trehalose derivatives could not be readily obtained in a considerably high yield and low cost.